Raw cotton fiber is typically contaminated with contaminants such as seeds or other cotton-plant matter, and a sticky substance secreted in the cotton by insects, called "honeydew". Honeydew is the result of infestation of growing cotton by aphids or white-fly. It takes the form of randomly distributed droplets of highly concentrated sugars, causing cotton stickiness. Such contaminants should be removed from the cotton fibers to as great an extent as possible in order to provide a higher quality cotton yarn. Honeydew presents unique problems due to its stickiness. It has been found that honeydew fouls cotton fiber and cotton yarn processing equipment, which ultimately increases the cost of manufacturing products from cotton. Fouled equipment must be shut down and cleaned, causing production down-time. Additionally, the product produced from contaminated equipment can be a lower grade, and thus have a lower value.
It has thus been found to be important to test the cotton fiber, before it is spun into yarn, for the presence and the amount of various contaminants. Vegetative matter is easy to see, and can be removed by combing. Honeydew, however, cannot be seen. The current tests for honeydew include the following. One manner of testing for honeydew is to use a small-scale production machine, for example a cotton yarn spinner, and run a portion of each bale of cotton through the machine and then inspect the machine for fouling. The results can then be extrapolated to the production environment. This, however, requires expensive, specialized equipment which is dedicated for such testing, and also results in the fouling of this equipment, which must then be cleaned. Accordingly, this test is somewhat slow, unsatisfactory, and ultimately expensive.
A second test involves taking a sample from each bale of cotton and sandwiching it in metal foil, and then heating the foil in an oven above the flash point of cotton to burn off the cotton. The honeydew tends to char more than the cotton fibers. After heating, the foil sandwich is removed from the oven and opened. The cotton fiber ash can be blown away. However, the honeydew ash remains as black char spots on the foil. The area of such spots can then be determined as an approximate measure of the area of the cotton fiber sample that is contaminated with honeydew. This test requires a fair amount of manual labor, and is also somewhat subjective, making it a less than ideal solution to the honeydew test problem.